Gilead Sciences spent $365 million to get a toehold in Seattle back in 2006, and so far, it has zero U.S. product sales to show for it. That’s made investors antsy, but it hasn’t deterred the world’s second-most valuable biotech company from continuing to bet big on Seattle as part of its plan to diversify away from its heavy reliance on HIV medications.

That was one of the interesting points I took home last Friday from Bruce Montgomery, the senior vice president and site leader for Gilead Sciences in Seattle. He made his comments during a talk at the Technology Alliance’s Science and Technology Discovery Series.

Foster City, CA-based Gilead (NASDAQ: GILD) has made a $50 million investment in a new 100,000 square-foot lab and office building along Eastlake Avenue in Seattle, Montgomery said. The local branch, which now counts 150 employees, hopes to move in to the new digs by February 26. The company is hoping that the new surroundings, with sweeping views of Lake Union, will inspire the local team to invent big new drugs. That’s because Gilead got about 90 percent of its $5.3 billion in 2008 revenue from antiviral treatments, mainly for HIV. While the HIV franchise has made Gilead a success, the company has spent several years trying to diversify with treatments for serious lung diseases and cardiovascular conditions.

The Seattle team is supposed to create big new treatments for lung diseases like cystic fibrosis, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis. But as of yet, the local team hasn’t delivered a blockbuster product. The heat is definitely on to start producing, at least in the eyes of Wall Street. Gilead stock dropped 15 percent in 2009, while the Amex Biotech Index composed of its large company peers climbed 45 percent.

Bruce Montgomery

“After a long and successful track record of product development, geographic expansion, and acquisitions, Gilead has recently fallen victim to slowing growth and execution missteps,” said Michael King, an analyst with Merriman Curhan Ford, in a note to clients Dec. 30. “Gilead Sciences has long been admired as a paradigm of drug discovery and development, as well as business execution. Having grown to a $45 billion market cap today on the basis of its HIV franchise, the company has recently experienced slowing growth as this franchise matures. In addition, the company has gotten little benefit from its $4 billion worth of acquisitions.”